Space heater



Oct. 28, 1958 W. l.. DAVIDSON Erm. y 2,857,906

SPACEA HEATER Filed Sept. l5. 1954 4 Sheets-Sheet 1 JNVENTOR:

Oct. 28, 1958 w. L. DAvlDsoN TAL 2,857,906

SPACE HEATER 4 Sheets-Sheet 2 Filed Sept. 13, 1954 JNVENTo er anniHyg/2471120 Pla if' n@ en@ n@ Oct. 28, 1958 Fired sepgc. 13. 1954 w. L.DAVIDSON ErAL 2,857,906

SPACE HEATER A4 Sheets-Sheet C5 -.E=== A m l-l Fil-1 l-l lll IN VEN T0#er L. DandRJja/r,

Oct. 28, 1958 W. L. DAVIDSON ETAL SPACE` HEATER 4 sheets-sheet 4 FiledSept. 15, 1954 United States Patent O SPACE HEATER Walter L. Davidson,Allison Park, and Abraham P. Loeb and Morgan P. QLaughlin, Pittsburgh,Pa., assignors to Dravo Corporation, Pittsburgh, Pa., a corporation ofPennsylvania Application September 13, 1954, Serial No. 455,592

1 Claim. (Cl. 126-110) The present invention pertains generally to spaceheaters of the type which discharge heated air through ducts to the areabeing heated or of the ductless type wherein the heated air isdischarged from the heater directly into the space to be heated by meansof adjustable hoods associated with the air outlets of the heater.

More specifically the invention relates to a combination of combustionchamber and convector plenums so related to each other and to the heatercasing so as to obtain improved heating eciency, minimum obstruction tothe ow of air through the casing and maximum ilexibility in the mountingof the heater within the area to be heated.

Space heaters of the duct type are well known in the art. Many differentdesigns of heaters and arrangements of the component parts thereof havebeen made in order to increase the efciency of such heaters. Spaceheaters of the ductless type are relatively new in the art and theseheaters in addition to the problem of increased efciency also presentadditional problems of economy in size and adaptability for mounting invarious positions within the area to be heated. The ductless heater byreason of being frequently mounted within a restricted space presentsthe compound problem of maximum eficiency, minimum space, and maximumflexibility in mounting.

The prior art in an endeavor to obtain increased efliciency providessuggestions for a plurality of passes of the combustion gases throughthe combustion chamber before discharge to the atmosphere through asuitable stack arrangement. In some instances the prior art alsosuggests passing the combustion gases exteriorly of the combustionchamber through some form of heat exchange unit to extract additionalheat from the combustion gases prioi to discharge from the heater. Allsuch arrangements known to the present inventors produces a rather bulkydesign of heater in which flow of heating air through the heater isusually impeded causing hot spots in the combustion chamber or heatexchange unit with consequential reduced heating efliciency andaccelerated deterioration of those portions of the heater in contactwith the combustion gases.

In the present heater, by reason of a novel form of combustion chamber,a plurality of passes of the combustion gases through the chamber areobtained and a maximum exposure of the heated surfaces of the chamber isprovided whereby the air to be heated flows freely `over these surfaceswith a minimum of obstruction, an

additional heat exchange unit, referred to herein as a convector plenum,is disposed above the top wall of the combustion chamber and in parallelspaced relation thereto so as to provide a plurality of passageway/sbetween the plenum and combustion chamber, between the plenums andthrough the plenums for the air flowing past the combustion chamber. Wehave used heat resistant metal to construct the combustion chamber andordinary steel to construct theplenums so that these members may beheated to a much higher temperature f'ce than is possible with ordinarysteels. The specific design of the chamber and plenums permits controlof the distribution of air to be heated passing over, beneath and aroundthe chamber and plenum so as to control the extraction of heat from themetal thus preventing hot spots which accelerate the rate ofdeterioration of the metal.

One object of the invention is to provide a combination of combustionchamber and convector plenum which offers a minimum obstruction toheating air passing thereover and distributes such air so as to preventformation of hot spots in the combustion chamber or convector plenum.

Another object of the invention is to provide a novel form of combustionchamber and convector plenum permitting improved extraction of heat fromthe combustion gases before being discharged from the heater.

A further object of the invention is to provide a novel form of mountingfor the combustion chamber within the heater casing permitting freeexpansion and contraction of the chamber, during heating cycles, whilethe heater may be mounted in a plurality of diierent positions.

These and other objects will be made apparent as the disclosureproceeds. In the drawings forming part of this disclosure, Fig. l is anisometric view of the heater showing the combustion chamber, convectorplenum, blower fan and casing with portions of the casing removed tobetter illustrate the arrangement of the parts;

Fig. 2 shows a side elevation of the heater of Fig. 1 with portions ofthe casing and combustion chamber removed to better show the flow ofcombustion gases through the chamber and plenum;

Fig. 3 shows the rear end elevation of the heater with a portion of thecasing removed to better show the arrangement of the combustion chamberand plenum in relation to the casing of the heater,

Fig. 4 shows a side elevation of the heater showing the arrangement ofthe casing;

Fig. 5 shows in detail a side elevation of the convector plenum;

Fig. 6 shows a rear elevation of the convector plenum;

Fig. 7 shows a section through the plenum taken along the lines VII-VIIof Fig. 5;

Fig. 8 shows a section through the plenum taken along the linesVIII-VIII of Fig. 5;

Fig. 9 shows a side elevation of the combustion chamber;

Fig. l0 shows a front elevation of the com'bustion chamber;

Fig. ll shows a rear elevation of the combustion chamber;

Fig. l2 shows a typical corner detail at lines XIl-XII of Fig. 4; and

Fig. 13 shows an enlarged detail of the casing support at lines XlI-XIIIof Fig. 3.

Referring now in detail to the drawings, reference character 1 refers ingeneral to the heater having an enclosing casing 2, combustion chamber 3and convector plenums d connected by a header plenum S. Beneath theco-mbustion chamber is an air baffle pan 6 having an opening 7 thereinregistering with the outlet of a blower fan 8 secured beneath the baillepan 6 and driven by a suitable motor 9. Above the combustion chamber, aheating air outlet in the casing has suitable hoods associated therewithfor directing the heating air in a plurality of directions.

The combustion chamber 3 comprises a front plate 10, side Wall portions11, bottom wall portions 12 and 13, top wall portions 14 and 15, ,and arear wall 16. The combustion chamber is of generally hexagonal shapehaving its longer axis disposed vertically. The chamber is Patented Oct.28, 1958 preferably made of stainless steel and of welded construction.For convenience in Welding, the front plate and rear wall 16 of thechamber are made slightly larger than the side, top and bottom walls sothat all welds can be of the lillet type and on the exterior of thechamber. Each top wall portion 14 and 15 is provided with a suitableopening 17 for passage of combustion gases from the chamber 3 into theplenums 4. These openings 17 are adjacent the front wall of the chamberand are enclosed by a suitable conduit 18 for attachment to the adjacentplenum. In the front wall of the chamber adjacent the lower portionthereof a suitable opening 19 is provided and enclosed by a burner tube20. Also on the front face of the combustion chamber adjacent the topthereof is an opening 21 enclosed by a tube 22 forming an observationport. Lifting lugs A and B may be provided on the respective front plate10 and back wall 16 of the combustion chamber for handling the chamberduring assembly of the heater, and may also be used for lifting theentire heater.

The convector plenums 23 and 24 are disposed above the combustionchamber top walls 14 and 15 in parallel spaced relation thereto. Theplenum 23 is disposed above the top wall 1.4 and the plenum 24 isdisposed above the top wall 15. Preferably, the outer side wall of eachplenum is disposed in substantially vertical alignment with the adjacentside wall of the combustion chamber, and the inner side wall of theplenum is disposed in spaced relation to the center line of thecombustion chamber as shown in Fig. 7. The plenums 23 and 24 thuscomprise hollow box-like structures extending from the inner face of thecombustion chamber front plate 10, across the combustion chamber andbeyond the rear wall 16 thereof. The ends of the plenums, adjacent therear wall of the combustion chamber, are connected by a header portion25. The header 25 is comprised of a continuous rear wall 26 spanning theplenums 23 and 24 with side walls 27 extending outwardly from theperiphery of rear wall 26 to conform to the slope of the plenum wallsand a front wall 28 lling the space between the adjacent plenum wallsand extending downward to the peripheral side Wall 27. Adjacent thefront wall of the combustion chamber, each bottom wall 29 of the plenumhas an opening therein registering with the opening 17 in the combustionchamber and the registering openings are connected by conduits 18 asshown in Figs. 5 and 8. Extending transversely through each plenum is ahollow box-like structure 30 having its top/and bottom walls disposed inspaced relation to the top and bottom walls of the respective plenum andhaving its side walls disposed in spaced relation to the side walls ofthe plenum. The ends of the members 30 protrude slightly beyond thevertical faces of the plenum members 23 and 24 as shown in Fig. 7. Themember 30 thus provides a passage for heating air through the member 30and combustion gases owing through the plenum pass around the member 30.The rear face 26 of the header 25 has an opening 31 therein and aconduit 32 mounted on the rear wall of the header in register with theopening 31 provides for exit of the combustion gases from the plenumheader to the atmosphere.

Within the casing 2 is a suitable support for the combustion chambercomprising a bottom pan 35 having at the corners thereof members 36connecting the bottom pan with the baffle pan 6. Adjacent each corner ofthe bottom pan is a suitable supporting member such as the angle 37supported on the bottom pan 35 and extending upwardly for connectionwith the under side of the bafe pan 6 by means of suitable clip members38. Disposed above the bathe pan 6 are a pair of frame members 39disposed adjacent the front plate 10 of the combustion chamber andsecured thereto. At the rear of the combustion chamber are a pair ofmembers 40 dis- 'posed on opposite sides of the combustion chamber butnot attached thereto. The members 39 and 40 on opl with the bottom wallsof the combustion chamber so vas to permit the combustion chamber tomove relative to the members 42 during expansion and contraction of thechamber'. .Adjacent the upper ends of the members 40 are the -supportingmembers 43 fastened to one leg of the members 40 and extending upwardlytherefrom so as to terminate in a flange 44 disposed beneath the wall 27of the convector plenum header 25 providing a support for the plenumheader upon which the header may move during expansion and contractionof the plenum and header. Adjacent the rear of the combustion chamber isa strap 45 engaging the top of the combustion chamber and extendingdownwardly along the top walls of the chamber so as to terminate in angeportions 46 overlying and welded to the members 40. This strap member 45is not connected to the combustion chamber but serves t-o retain thechamber and associated plenum in xed relation to the supports 43 and 42when the heater is mounted in an inverted position. Each of the members39 and 40 have secured thereto, in vertically spaced relation,separators 47 having one end secured to the members 39 and 40 as bywelding, the opposite end of the members 47 having a plate washer 48welded to the member 47 to serve as a spacer for the casing members. Theseparator 47 is provided with internal threads.

The outer casing of the heater may be mounted upon 'y the abovedescribed combustion chamber supporting frame in any suitable manner.One method of supporting the casing would be to provide the casing sidesheets 50 and 51 with side flanges to which would be secured the rearcasing sheet 52 and front casing sheet 53 as ,shown in Fig. 12. Sheet 52is provided with a suitable opening through which the plenum headerconduit 32 extends and the sheet 53 is provided with suitable openingsthrough which the burner tube 20 and observation port tube 22 extend.The side sheets 50 and 51 are provided with suitable lateral supports bymeans of the anges 54 of the bafe pan 6 and provided with vertical andlateral support by means of stud bolts 55 extending through the casingsheets and threaded into the separators 47 secured to the combustionchamber frame members 39 and 40. The upper ends of the casing sheets50-51 would conform to the slope of the upper surface of the plenums 23and 24, being disposed in spaced relation thereto, and joined by asuitable collar 56 extending over and secured thereto. The casing sheets52--53 would extend vertically upward with their upper ends conformingto the slope of the side sheets 50 and 51 so as to be disposed beneathand connected with the collar 56. Disposed upon the collar 56 is anozzle pan 57 of suitable design for attachment to the collar andprovided with apertures 58 for reception of the air directional nozzles59. The casing about the combustion chamber when constructed in thismanner will have adequate vertical support as well as transverse supportsupplied by the stud bolts 55 which are anchored in the framing members39 and 40, and their lower ends secured against lateral displacement bymeans of the lianges 54 of the baffle pan 6. The portion of the casingabout the blower fan is preferably formed of casing members 60 providedwith louvers 61 and secured to the bottom pan 35 and bale pan 6. Asclearly shown in Figs. 3 and 4 of the drawings the outer casing sheets50 and 51 are supplied with a suitable bearing by means of the washerplates 48 and may be provided with an additional plate Washer 62disposed upon the outer face of the casing sheets and beneath the headof the stud bolt 55, as shown in Fig. 13.

Within the casing and adjacent the casing plates 50 51-52-53 arepreferably provided heat shields 63. These are preferably of heatresistant metal such as stainless steel and disposed in slight spacedrelation to the outer casing sheets, as shown in Fig. 12. These heatshield sheets 63 are preferably provided with side flanges secured tothe adjacent casing sheets and at the sides of the casing are providedwith suitable openings for passage of the separators 45 which providevertical support for the casing sheets. As clearly shown in Figs. 3 and4 of the drawings the upper ends of the heat shields 63 secured to theside sheathing plates 50 and 51 extend upwardly for substantially thefull length of the latter sheets and conform to the contour thereof. Atthe corners of the casing, corner heat shields 63a are provided.

During operation of the heater, it may be mounted upon its base 35 asshown in Fig. 1 of the drawing, or it may be suspended in an invertedposition. Where desirable it may be mounted in a horizontal position.When inverted the combustion chamber supporting members 39 and 40 byreason of their connection with the chamber, either directly or throughstrap 45, retain the chamber in operating position. A suitable burner 64is mounted in the burner tube 20. Such a burner may be any one of thecommercial forms now available and preferably adapted for burning eitheroil or gas. A fan and limit switch 65 may be provided in the upperportion of the casing and a stack switch 66 may be mounted in thecombustion gas outlet conduit 32 for automatic control of the operationof the heater. A suitable control panel 67 may be mounted on the casingand connected with the fan, stack and burner controls. A suitable stack(not shown) would be connected with the conduit 32. The design of theheater makes it suitable for natural draft operation, but forced orinduced draft may be used where desired.

After the burner is placed in operation, the combustion flame ispreferably adjusted so as to direct the burning fuel to adjacent therear wall of the combustion chamber as shown in Fig. 2 of the drawings.Due to the natural draft of the stack the combustion gases will then bedeflected upwardly and flow towards the front wall of the combustionchamber where they will pass out of the chamber through the openings 17and the conduits 18 inthe top wall portions 14-15 of the combustionchamber into the converter plenums 23 and 24. The combustion gases willthen flow through the convector plenums and around the members 30 intothe header 25 adjacent the rear of the heater where they will beaccumlated and pass through the conduit 32 into the stack and to theatmosphere. The heater is provided with suitable automatic controls sothat after the combustion chamber and plenum had been raised to asuitable temperature, the blower fan is started to and blows air intothe substantially closed combustion chamber casing as shown in Fig. 2 ofthe drawings. The air from the blower flows upwardly about all surfacesof the combustion chamber and at the sides of the chamber flows throughthe spaces 70, between the plenums and the top wall of the combustionchamber, into the space 71, between the inner ends of the plenums andoutwardly through the nozzles 59. Some of the air passing upwardly alongthe sides of the combustion chamber will ow through the member 30 intothe spaces 71 and other portions of the air flowing upwardly from thesides of the combustion chamber will flow between the top walls of theplenums and the heat shields 63 to the nozzles 59. Likewise at the sidesof the combustion chamber the air will flow between the heat shields 63and the sides of the outer sheathing cooling the sheathing and passupwardly to the nozzles 59. At the front of the combustion chamber theupwardly flowing air will wipe the front plate of the combustion chamberand flow to the nozzles 59. At the rear of the combustion chamber theupwardly tiowing air passes over the header portion 25 in flowing to thenozzles 59. The spacing between each convector plenum and the top wallof the combustion chamber, as well as the size of all the other airpassages hereinbefore recited, can be of such size as to adequately anduniformly cool the adjacent surfaces preventing hot spots. By reason ofthe use of stainless steel the combustion chamber and plenums can beraised to a high temperature which contributes to the efficiency of theheater. As will be apparent from an examination of the drawings tiereare no abrupt changes of direction of the heating air ilowing over thecombustion chamber and convector plenums which would also contribute tohot spots.

The details of construction shown on the drawings are for purposes ofillustration and not limitation except as necessitated by the scope ofthe appended claim.

ln a space heater, a closed combustion chamber having side walls, a topwall connecting said chamber side walls and having opposite facesconverging inwardly and upwardly from each side wall, a bottom wallconnecting said chamber side walls, and front and rear walls connectingsaid side, top and bottom walls, said front wall having an extensionabove said top wall, a substantially rectangular hollow convector plenumdisposed above each converging face of the chamber top wall in parallelspaced relation thereto, the opposing adjacent inner side walls of saidplenums being spaced from each other to provide an air passagewaybetween them above the connected converging faces of said chamber topwall, a conduit connecting the interior of each plenum with the interiorof the combustion chamber through the adjacent chamber top wall anddisposed adjacent the charnber front wall, a header connecting the endsof the plenums adjacent the said chamber rear wall, means attaching saidchamber front wall extension to the adjacent ends of the plenums, therebeing openings in opposite side walls of each plenum and a hollow memberextending between said openings, said hollow member being secured to theconvector plenum side walls forming a passageway through which airpasses into said air passageway and about which combustion gases ow inpassing from the combustion chamber to the plenum header, a casingenclosing the combustion chamber and the plenums, said casing havingside, front and rear walls spaced from corresponding walls of thechamber and plenums directing air to be heated over such latter wallsand through the spaces between the plenums and chamber walls and throughthe passageways of the plenums, a heated air outlet in the casing abovesaid chamber, a combustion gas outlet conduit extending through saidcasing into the plenum header, means forming a registering inlet openingin the front face of the combustion chamber and casing, a combustionburner nozzle extending through said openings, and means including a fanwithin the casing disposed below said combustion chamber for forcing airto be heated over said chamber and plenums to said heated air outlet.

References Cited in the le of this patent UNITED STATES PATENTS1,218,288 McPherson Mar. 6, 1917 1,634,706 Carroll July 5, 19271,991,449 Cornelius Feb. 19, 1935 2,109,876 Bard Mar. 1, 1938 2,114,584Aunger Apr. 19, 1938 2,160,269 Jorolemon May 30, 1939 2,172,667 NelsonSept. 12, 1939 2,376,140 Henderson et al. May 15, 1945 2,430,393 ElmoreNov. 4, 1947 2,514,011 Ruff July 4, 1950 2,555,842 De Lancey June 5,1951 `2,612,153 Gibler Sept. 30, 1952

